You connected to PostreSQL perfectly, but your credentials were rejected. Your issue is either with the credentials you used (bad username/password), or with the pg_hba.conf file. Is uDig installed on the same computer as QGIS? What does your pg_hba.conf file look like?

You connected to PostreSQL perfectly, but your credentials were rejected. Your issue is either with the credentials you used (bad username/password), or with the pg_hba.conf file. Is uDig installed on the same computer as QGIS? What does your pg_hba.conf file look like?

The error message shows a host name that resembles an IPv6 address "fe80::5d19:5338:ab5b:14f9%10" (except it isn't due to the "%10" part), but you appear to only have an entry for IPv4 addresses. If you have full trust of your network, try adding this line to pg_hba.conf, then reload the PostgreSQL server:

# Allow all IPv6 connections
host    all             all             ::/0                 trust

The default port for PostgreSQL is 5432, not 54321.

You connected to PostreSQL perfectly, but your credentials were rejected. Your issue is either with the credentials you used (bad username/password), or with the pg_hba.conf file. Is uDig installed on the same computer as QGIS? What does your pg_hba.conf file look like?